The primary object of this invention is to arrest a heavy vehicle traveling at high velocity, by means of an obstruction member extending transversely of a trafficway and subject to the inertia of an above grade mass. In a first and basic embodiment of the barrier is an integral mass as taught in U.S. Pat. No. 4,490.068. In a second and preferred embodiment the mass is separated by an obstruction member as taught in U.S. Pat. No. 4,844,653. Force is applied to and dissipated by the obstruction member of either embodiment and limited to the mass inertia thereof, and in the second embodiment the separated masses are in equilibrium with each other, whereby in either embodiment the obstruction member is subjected only to the yielding mass, the greater impacting force of the vehicle being absorbed in accelerating the mass or masses of this apparatus.
This invention relates to anti-terrorist barriers capable of stopping the movement of vehicles unauthorized to enter through a trafficway, and is an improvement over the aforementioned U.S. Patents, wherein the barriers are fixedly installed below grade, and wherein means is provided to fixedly anchor an arresting cable to opposite sides of a trafficway. This prior art also provides means that swivels the cable carrying beam at a first side of the trafficway, to rotate in a horizontal plane during impact. And this prior art also teaches the use of frangible parts at what is termed the pivot block of the semiphore device, so as to permit horizontal rotation thereof upon vehicle impact. And characteristically, this prior art teaches fixedly positioned barriers and cable anchor means, the structure being cemented into fixed positions below grade.
A vehicle moving toward a barrier of the type under consideration has kinetic energy which is calculated by the vehicle gross weight times the square of its velocity, and upon impact with such a barrier this kinetic energy is then converted into heat, sound and mainly into the deformation and destruction of the vehicle whereby the vehicle is demolished. And in accordance with this invention the barrier has inertia that is absorbed by the kinetic energy released upon vehicle impact with an obstruction member of the barrier. In actual practice, the total energy dissipated depends upon varying factors prevailing at the time of impact, all of which need not be detailed here. For example, the barrier shown and described herein will destroy a 15,000 pound (gross) weight vehicle impacting at a velocity of 30 MPH and much more. And it is to be understood that vehicles vary greatly in weight and structural durability, that trafficway alignment will vary, and that vehicle velocity can be more or less than the example given here. Accordingly, it is a general object of this invention to provide a yielding barrier, characterized by its shiftable mass. In the second and preferred embodiment said mass is comprised of spaced inertia blocks between which and obstruction member is visibly carried by a retractile semiphore beam.
This barrier can take various gate type forms and is shown herein as a semiphore beam that carries a hidden obstruction member having improved properties to extend across a trafficway between massive inertia blocks to which it is joined in a xe2x80x9cclosedxe2x80x9d and effective position. In the xe2x80x9copenxe2x80x9d ineffective position the obstruction member is detached from one inertia block and swings away from the other inertia block, the two massive inertia blocks being at opposite sides of the trafficway. The barrier is also shown in its basic form as a rigid above grade structure extending transversely over the trafficway surface, wherein the obstruction member is a wall that is raised and lowered within a rigid and permanent frame structure.
An object of this invention is to effectively tie two masses together with a vehicle obstruction therebetween, and all of which are inseparable upon vehicle impact. In practice therefore, the obstruction is a flexible member of great strength and which conforms to vehicle deterioration during impact. And the masses are blocks that are shiftable upon vehicle impact according to the magnitude of the kinetic energy absorbed thereby.
It is a primary object of this invention to totally arrest motion of the impacting vehicle. And, upon slight impact the system yields if at all and shifts very little, whereas upon great impact the system yields and shifts substantially. The flexible obstruction member then becomes a snare attached to spaced massive inertia blocks and each of which is shiftable and subject to displacement from its initially deposed position. In accordance with this invention, it is therefore an object to provide repositionable inertia blocks subject to displacement when arresting the momentum of a vehicle to an absolute stop.
It is an object of this invention to provide a beam support for the flexible obstruction member in the form of a chain, by which the chain is retractably carried to fasten between the two shiftable inertia blocks, the chain being an improved obstruction member as hereinafter described. The beam is tubular so as to enclose, support and hide the chain, and it is adjustable as to length so as to accomodate the attached effective length of said chain. In practice, the beam is an extension tube that is expendable after a vehicle impact and which telescopes into a yoke tube that is swiveled so as to swing as a semiphore away from its operative transverse position. The extension tube is initially straight and guides end links of the chain into alignment with clevis pins by which the supported chain is detachably secured to the inertia blocks at opposite sides of the trafficway.
This barrier system provides a pair of spaced massive above grade inertia blocks from each of which a vertical column projects for the attachment of the obstruction member extending therebetween above the trafficway. Each vertical column is preferably a steel weldment approximately 30 inches tall (above grade) secured to a steel frame to which the inertial mass is assembled. The assembly remains free and detached from the grade level upon which it is deposed.
It is an object of this invention to provide yieldable placement of the above surface mass or spaced masses of this barrier system. In the spaced block embodiment, predetermined absorbtion of kinetic energy as caused by vehicle impact requires control of two factors; 1) the inertia of the individual blocks, the levers and obstruction member assembled therebetween; and 2) the friction properties of the interfaces of the spaced masses with the grade surface upon which they are deposed.
In accordance with this invention the spaced blocks simply rest upon the grade surface such as concrete or asphalt paving, soil, or any such combination thereof. To this end the massive structural weight or weight of the blocks are displaced according to the deceleration forces applied during the transfer of momentum when absorbing kinetic energy as a result of vehicle impact, followed by frictional retardation of said blocks as kinetic energy that is completely dissipated. A feature herein is the total release of kinetic energy as a result of deceleration of the vehicle velocity to a fully stopped condition.
Heretofore, the obstruction member of gate type semiphore barriers has been a steel cable carried by a tubular beam extending between a pivot post rigidly cemented into a permanent foundation at one side of a trafficway, and a bit post rigidly cemented into a permanent foundation at the other side of the trafficway. Accordingly, the prior art barrier systems have been predicated upon immovable foundation blocks with frangible parts, and limited in vehicle impact momentum. As a result, permanent foundation blocks shift and are tilted out of alignment and therefore require rebuilding. And, steel cable fails and is xe2x80x9csnappedxe2x80x9d when impacted by heavy high speed vehicles. It is an object of this invention therefore to provide a barrier system that avoids major replacement of structure by combining said structural members so as to avoid damage and which are readily re-aligned with the trafficway, and above all an obstruction member in the form of a chain.
The elements essential to this invention are the singular or multiple above grade mass and the obstruction member coupled thereto and extending transversely of the trafficway. It is the controlling planar interfaced deposition upon and frictional engagement with the supporting grade surface that characterizes this barrier concept.
This is a crash rated wall or gate type vehicle, barrier system that can be quickly deployed or relocated as circumstances require for manual or automatic operation. The mass or masses do not require any excavation or foundation construction. The inertial mass is either an integral structure or separate masses located at opposite sides of the trafficway and assembled of interlocaking sections from which spaced posts extend upwardly to suspend the obstruction member therebetween. The assembly can be filled in situ with concrete, sand, gavel or other available mass media or alternately at a remote location or at the point of manufacture. Each weighted assembly presents a significant mass as may be required, whereas an unfilled assembly is light-weight for shipping. Each assembly has features for forklift handling etc., and the systems can be operated manually or by fully automatic control.